Authorities are working to negotiate the release of a young Perth couple who have been imprisoned in Iran for more than two months.
Australian man, Mark Firkin, and British-Australian woman, Jolie King, had been backpacking around the world in their 'Troopy' Toyota Land Cruiser and vlogging their adventures.
They were arrested in July after taking photos while camping at a military precinct in Tehran province and are being held in the notorious Evin Prison - used to house Iran's political prisoners.
The couple resigned from their jobs in mid-2017, and embarked on a two-year journey to drive across 36 countries to reach the UK.
They had already travelled through Western Australia's north west, Indonesia, India and Pakistan.
A spokesperson for Australia's Department of Foreign Affairs (DFAT) confirmed it was providing consular assistance to the families of the the couple, and another older Australian woman who is detained in Iran.
The third woman, who is a Melbourne university lecturer, was detained in October while travelling the country and has been sentenced to 10 years' jail.
"Due to our privacy obligations, we will not comment further," the spokesperson said in a statement, before urging travellers to follow the DFAT travel advice in place for Iran.
That advice urges Australians to "reconsider your need to travel".
Another woman, Iranian-Australian dual citizen and Melbourne University academic Meimanat Hosseini-Chavoshi, was arrested in December last year as she attempted to leave Iran, as previously reported.
Hosseini-Chavoshi, who is a population expert affiliated with the Melbourne School of Population and Global Health, was charged with trying to "infiltrate" Iranian institutions.
A source close to Hosseini-Chavoshi says she has been released on bail, but has not been allowed to leave Iran while the investigation into her case is under way.
DFAT's Smart Traveller website warns that "foreigners including Australians could be arbitrarily detained or arrested".
In August, the deputy chair of Iran's foreign relations parliamentary committee Kamal Dehghani Firouzabadi warned Australia's "reputation and prestige" would suffer after they joined a US-led military coalition to protect shipping in the Strait of Hormuz.
British forces seized an Iranian oil tanker in July, claiming it was destined for Syria. Two weeks later, Iran seized British oil tanker, the Stena Impero. The Iranian tanker was later released. The Stena Impero is still being held by Iran.